Abstract:Straw mulching of farmland is a main method to reduce soil erosion and to improve water retention. However, overmuch straw mulching may lower the antiblocking capacity of notill planter, which is important to production efficiency and seeding quality. This research aims at discussing the influence of maize straw mulching on infiltration and sediment yield process under different soil texture conditions, and concluding an appropriate straw mulching rate for the optimization of notill planter performance as well as the conservation of water and soil in the conservation agriculture research areas of north China. A rainfall simulation experiment was carried out from October to November in 2014, and the experimental field was located at Experimental Station of China Agricultural University, in Zhuozhou City, Hebei Province, North China. The runoff monitoring site was designed as a Vshaped symmetrical distribution, composed of six experimental plots. A UGT runoff measuring device made in German was installed to monitor the runoff and sediment yield process, and maize straw was collected cut off (less than 100mm) after maize harvesting (early October). Two kind of soil type (sandy soil and loam soil) and five kind of straw mulching rate (0, 10%, 20%, 30%, 40%) were considered as two independent variables in experimental design (three repeated). Each simulated rainfall lasted 1h. The impacts of maize straw mulching on infiltration and sediment yield were analyzed. The results indicated that straw mulching delayed runoff time, enhanced infiltration, and reduced soil loss. Specifically, 30% straw mulching treatment significantly enhanced accumulative infiltration by 25.7%~33.9%, reduced soil loss by 22.2%~46.4%, compared with no mulching treatment. The experimental results also showed that the erosionresistance of soil under different texture was different: under a 1h simulated rainfall with 80mm/h rainfall intensity, the steady infiltration rate and accumulative infiltration in loam soil were 0.02mm/min and 5.9mm less than that in sandy soil condition, and the corresponding total sediment yield was less by 1.364g compared with sandy soil. Although 10% mulching treatment under sandy soil condition reduced soil loss significantly, the total sediment yield was much greater than that of loam soil in 10% mulching treatment. So least straw mulching rate of 30% was recommended on farmland surface in sandy soil and loam soil of north China, comparing the water and soil conservation effect of straw mulching under different soil texture conditions. However, in conservation tillage fields, over mulching (>80%) may lower the antiblocking capacity of notill planter, and thus affected seeding quality and grain production in north China. In conclusion, in conservation tillage system of sandy soil and loam soil planting area, 30%~60% maize straw mulching (1600~3000kg/hm2) is recommended to achieve high performance of planting and high efficient soil and water conservation, which provides the valuable information for suitable straw mulching rate of maize in north China during the application of conservation tillage practice.
